The Clinical Core is a critical component of the ADRC. The Specific Aims of this Core are: 1) To follow annually, in person, a subset of previously recruited subjects (normal older adults, mild AD and Mild Cognitive Impairment (MCI) patients). Those patients who have transitioned to moderate/severe AD will be followed by telephone interviews. 2) To annually follow and recruit and 30 normal older adults, 30 MCI, 30 mild AD and 30 Parkinson's disease with dementia patients yearly with approximately 20-25% being African American. 3) To perform baseline and annual neuropsychological assessments on all recruited subjects. 4) To make available patients, caregivers, neuropsychological and clinical data to the leaders of the three ADRC Projects and to other investigators needing this information or subjects. 5) To continue to solicit and arrange autopsies on all subjects. 6) To work closely with the Data Management and Biostatistics Core to ensure that our data is of the highest quality and to ensure that it is transmitted to NACC in a timely fashion.